1. Field of the Invention
The present invention relates to a system and composition useful in indicating the occurrence of chemical vapor sterilization. More particularly, the present invention relates to a composition which undergoes a change in appearance when exposed to the hydrogen peroxide used in a chemical vapor sterilization process.
2. Brief Description of the Prior Art
Methods using steam and disinfecting gases, particularly ethylene oxide, have been widely used for sterilizing medical products ranging from pharmaceutical preparations to surgical instruments. A sterilizing method must effectively render all microbial organisms non-viable without damage to the article or goods being sterilized or its packaging. However, many disinfecting gases which meet this criteria, such as ethylene oxide, have been recognized to expose workers and the environment to safety hazards. As a result, alternative methods have emerged, among which are the low temperature chemical vapor phase sterilization techniques.
The recent emergence of chemical vapor phase sterilization technology operating well below temperatures associated with steam sterilization has created the need for new indicator materials/systems. These "low temperature" technologies, operating below 176.degree. F., and generally below 150.degree. F., share a common property that the sterilized goods are available for use shortly after the completion of the sterilization cycle. This property distinguishes these sterilization processes from sterilization by ethylene oxide, which also operates in the specified temperature range, but requires lengthy aeration of the sterilized goods due to the toxicity of residual ethylene oxide. In contrast, the new processes are intended to rely heavily on the presence of hydrogen peroxide whose non-toxic decomposition products are water and oxygen. The potency of the hydrogen peroxide may be augmented by the presence of peracetic acid and/or electrical energy in the form of an ionizing plasma field.
There exist a variety of indicating compositions, and coated media, for visualization of the presence of aqueous solutions of hydrogen peroxide. For example, U.S. Pat. No. 3,183,173 teaches the use of filter paper impregnated with iodide and molybdate salts in a buffered polyvinyl alcohol solution. The paper is useful for the detection of aqueous solutions of hydrogen peroxide.
See also, Diebold, Rapkin and Usmani (Chemtech, August 1991, pp. 462-465), who describe systems such as hydrogen peroxide-tetramethylbenzidine and hydrogen peroxide, 4-aminoantipyrine and phenol which yield color products useful for determining the presence of glucose and cholesterol. In both cases hydrogen peroxide is a product of the reaction of the analytes (glucose or cholesterol) and thus its detection is a secondary measure of the analytes.
U.S. Pat. Nos. 5,326,388, 5,352,282, 5,486,228 and 5,492,558 describe the selective high pH bleaching of coated materials by liquid reactants including hydrogen sulfide, sodium sulfite, sodium hypochlorite, and hydrogen peroxide. In particular, the patents describe a multiple coloring composition system whose coloring effect is changed upon treatment with a second coloring composition upon depositing the second coloring composition over the first coloring composition. The first coloring composition comprises a dye whose coloring ability is destroyed in the presence of a bleach. The second coloring composition, which is used to change the coloring effect of the first composition, contains bleach and a colorant capable of maintaining its characteristic color in the presence of the bleach. Among the dyes found in the bleachable coatings are Astrazon Brilliant Red 4G (Basic Red 14) and Astrazon Pink FBB (Basic Red 49).
A suitable indicator imminently useful with the new chemical vapor phase sterilization processes would be valuable to the industry.
Accordingly, it is an objective of the present invention to provide a color change composition useful in indicator materials for indicating the vapor phase sterilization of an article.
It is yet another object of the present invention to provide systems for indicating vapor phase sterilization of an article, employing such color change compositions.
Yet another object of the present invention is to provide a process for indicating when an article has been subjected to a sterilization process.
These and other objects of the present invention will become apparent upon a review of the following specification and the claims appended thereto.